The origin of the bird fauna of the south Venezuelan highlands. Bulletin of the AMNH ; v. 136, article 5

Abstract:

"The isolated tabletop mountains in southern Venezuela (including Roraima and Duida), the adjacent border of Brazil, and Guyana are the home of an interesting highland avifauna rich in endemics. We have designated the area as Pantepui. 2. The history of the ornithological exploration of these mountains, beginning in 1842 with the work of the Schomburgks, is presented. Birds have been collected on a total of 26 cerros and tepuis. Of the approximately 10,750 specimens taken, 8340 are in the Phelps Collection in Caracas. 3. Ninety-six species can be considered typical subtropical elements. Twenty-nine of these are endemic species or superspecies. 4. The subtropical elements are found on the summits and in the cool humid forests of the talus slopes. 5. About two-thirds of the characteristic elements are widely distributed in the Pantepui area. Five species have not yet been found east of the Río Caroní; 18 species are found only to the east of it. 6. Many (viz., 42) species are represented on Pantepui by several subspecies, six in the case of Atlapetes personatus, five or four in several other species. Nine of the 29 endemic species are monotypic. Two species have evolved into superspecies. 7. The 96 Pantepui elements represent every stage of endemicity, from endemic genera (two or three weakly characterized ones) and species (29), to non-endemic species with endemic subspecies (55), and non-endemic species without endemic subspecies (12). 8. The 96 Pantepui species can be assigned to four kinds of faunal elements: (a) specialized cliff dwellers (five species), (b) altitudinal derivatives of elements that are tropical in other areas (34), (c) long-distance colonists which reached Pantepui by 'hopping' across the unsuitable lowlands (48), and (d) old endemics which may have originated as either (b) or (c) (nine). 9. Many species exhibit strong geographic variation in habitat preference. Basically subtropical species may have tropical populations and vice versa. Such plasticity unquestionably facilitates the crossing of ecological barriers, such as lowlands present for mountain birds. 10. Among the 48 species of long-distance colonists 24 species presumably came from the Andes; 19 species, from the coastal cordilleras of northern Venezuela; and five species, from more distant areas. 11. The small number of old endemics indicates a rapid replacement in the bird fauna of these mountains, which must have existed for some 30 million years. 12. Although a few of the Pantepui endemics can be called relicts, they are not remnants of a formerly more widespread fauna, which is now extinct elsewhere. Most endemics belong to the most actively speciating genera and families of South American birds"--P. 307.

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Bulletin of the American Museum of Natural HistoryThe Bulletin, published continuously since 1881, consists of longer monographic volumes in the field of natural sciences relating to zoology, paleontology, and geology. Current numbers are published at irregular intervals. The Bulletin was originally a place to publish short papers, while longer works appeared in the Memoirs. However, in the 1920s, the Memoirs ceased and the Bulletin series began publishing longer papers. A new series, the Novitates , published short papers describing new forms.